I am categorically not the gym type. My body consciousness is not quite at that crushed point of turning off the lights before sex. But it is almost.

At 33 I am 5ft 10in and erring the wrong side of 13 stone. My shape needs to be addressed. A week's intensive fitness programme on the glorious Kenyan coastline seems too amiable an introduction to pass up.

"We aren't here to turn you into a sportsman," says Jacob, one of the trainers, on my first shaky day at Wildfitness. This appeals to me, though not half as much as when he attributes my stealthily nurtured, ever expanding stomach to a strange dip in my lower spine (and there was me thinking it had something to do with Guinness). Jacob doesn't like my posture and tries not to look overly aghast at my lifestyle. There is almost a hugging moment when I tell him I have recently gone dry, though I subtly fail to mention that this was a pre-emptive strike to avoid the next logical step in my drinking life: AA.

The regime itself feels less gruelling than it is. The day begins with a wake-up call at 5.30am. There is an exercise session before breakfast, taking into account your personal degree of elasticity (mine: not very), one between breakfast and lunch, and another between lunch and dinner.

Nothing is enforced, but the presence of a man twice my age who gamely gets into it all shames me into trying everything. The trainers push without pressurising you, and the sessions mix jolly team games with one-on-one holistic and therapeutic practices. From bouncing on a Swiss ball (pre-breakfast) to pumping iron (post-) or joining in an assault course (pre-tea), there is a degree of fun to the activities that I hadn't bargained for in the pursuit of wellbeing. It isn't a boot camp, it's a genuine vacation. There are even treats: a massage on the sun-dappled beach proves a particular highlight.

We never do the same thing twice. Whether it is the dizzying splendour of the Kenyan backdrop, the strict but strangely appealing diet (no sugar, caffeine or salt; "insidious poisons", they call them) or the weightlessness of having nothing else to do, by day three I have magically morphed into a fitness person. Volleyball is fun; boxing, something I had previously confined to fleeting erotic fantasy, is a revelation.

By day five, I have completed a 6km forest run and got the kind of head rush I would have once figured came only from illegal substances. "Feels like ecstasy, huh?" quizzes Jacob. I pant a sort of affirmative response. On day six I do a triathlon. At 6am. This was never, ever sketched into my lifeplan.

Wildfitness didn't change my life, but it proved that luxury is a fortuitous introduction to fitness. I tried jogging in a local Hackney park a couple of times on my return, but the litter and kids dissuaded me. Vanity may save me yet, though. I've lost a stone. People notice. In the fullness of time, I may discover my inner athlete. I think he's struggling away in there somewhere, bless him, and it was nice to meet him for a week.